This invention relates generally to non distructive testing and more specifically to a method and system for measuring the size of defects not otherwise capable of being directly measured.
Since the introduction of jet engines to aviation, damage to the compressor turbine blades by either foreign or domestic objects has been a big problem. Once a blade or blades other than in the first or last stages have been damaged, the engine must be torn down in order to measure the damage. In the more recent engines, apertures have been designed into the engines in critical areas so that with the aid of a borescope, the blades may be viewed optically and photographed with the aid of photographic attachments to the borescope. This allows a determination of the nature of the defect but not its size, which is a critical factor.